<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link type="text/css" href="./css/box.css" rel="stylesheet"/>
</head>
<body>
  <!-- 盒模型 -->
  <div class="content-box"></div>
  <div class="border-box"></div>
  <!-- BFC -->
  <div class="bfc">
    <div class="bfc-child1"></div>
    <div class="bfc-child2"></div>
  </div>
</body>
</html>